Field of the Invention and Related Art Statement
The invention relates generally to a video signal recording and reproducing technique, and more particularly to a video recording apparatus for effecting video edition and superimposition.
There has been often used a video tape recorder (VTR) for the production of programs in TV broadcasting. In such known recorders, scenes picked-up by one or more television cameras are recorded on one or more video tapes by a VTR and these video tapes are edited to make a master video tape for broadcasting. To edit the tapes there has been developed a splice editing technique in which a tape is cut into portions and necessary portions are spliced and electronically edited with the aid of an editing VTR. The latter system is now widely used because automatic editing by computer control is possible and various special effects can be given in addition to simple cuts. Further, when producing a program for broadcasting, there is frequently used superimposition for superimposing characters, patterns and the like on the image.
FIG. 1 shows a known typical electronic editing system, comprising two reproducing VTRs 1, 1', one recording VTR 2 and a mixing amplifier 4 arranged therebetween, the reproducing VTRs, recording VTR and mixing amplifier being controlled by an editing device 3. This system is usually called an A:B roll editing system. In this editing system, original tapes A and B (the original tape B is generally made by dubbing the original tape A) are loaded on the reproducing VTRs 1 and 1', respectively, and reproduced video signals are selectively recorded on a master tape M loaded on the VTR 2 through the mixing amplifier 4, so that images can be superimposed one upon the other, and the video effect is actively increased. However, this known system disadvantageously requires three sets of expensive VTRs.
Since the editing device 3 synchronously drives three VTRs, a considerably highly efficient synchronizing mechanism is necessary, and as a result, the greater number of required VTRs, the more expensive the editing system. Further, in the known editing system, even if a part of the master tape lasting only a few seconds is to be further edited, the whole program should be dubbed by loading the master tape in the reproducing VTR. Such dubbing takes a long operating time and causes inevitable deterioration of video signals.
FIG. 2 shows another known system for superimposing characters, patterns and the like on a part of the master tape which has already been edited. The edited master tape M is loaded on a reproducing VTR 1, a new master tape M' is loaded on a recording VTR 2, and character signals generated by a character generator 5 or a television camera is supplied to the recording VTR 2 through a mixing amplifier 4. Such a system requires two sets of VTRs only for superimposing characters, becomes considerably expensive, has to dub the whole program for superimposing characters on a part of the picture image, causes unnecessary deterioration of the video signal and takes a considerably long period of time for editing.
As described in the foregoing, the known video recording apparatus for editing requires many expensive VTRs, and is complicated, large and disadvantageously expensive. Further, since each time only a part of the program is to be subjected to superimposition and replacement, the whole program should be dubbed, the operation time becomes long and deterioration of the video signal cannot be avoided.